Newark Mayor Cory Booker, a Democrat, is running for an open U.S. Senate seat in New Jersey. / Stephen Lovekin, Getty Images

by Catalina Camia, USA TODAY

by Catalina Camia, USA TODAY

WASHINGTON -- The race for New Jersey's open U.S. Senate seat has begun in earnest, as candidates scrambled to meet Monday's filing deadline and two new polls showed Newark Mayor Cory Booker to be an early favorite for the Democratic nomination.

Booker has support from more than 50% of Democratic voters in the Rutgers-Eagleton and Quinnipiac University surveys, the first to be released in the unusual special election. Rep. Frank Pallone mustered only single-digit support in both surveys, while Rep. Rush Holt did slightly better and garnered 10% support in the Rutgers-Eagleton survey.

The Oct. 16 special election will determine who will serve the remainder of Democrat Frank Lautenberg's term, which ends in January 2015. New Jersey Attorney General Jeff Chiesa, a Republican, was sworn in Monday afternoon to serve as the interim replacement to Lautenberg, who died last week.

"It's Newark Mayor Cory Booker in a runaway in this first look at the special election," said Maurice Carroll, director of the Quinnipiac University Polling Institute. "Who are those other guys? The record shows that Congressmen Frank Pallone and Rush Holt are big in their districts but, statewide, no one knows them."

Booker announced he has the support of George Norcross, a former chairman of the Camden County Democratic Party and a longtime power broker in South Jersey. Political analysts say support from county chairmen, who can crank up their machines and get out the vote, will be crucial in the Aug. 13 primaries.

Booker "has the highest name recognition and that makes him the favorite. The question that we have is how many of his voters will actually show up in the primary," said Patrick Murray, founding director of the Monmouth University Polling Institute.

"You've got to get people knocking on doors in a primary that will be low turnout," Murray said. "It's all about organization."

The two polls were taken before state Assembly Speaker Sheila Oliver officially jumped into the race on Monday.

All candidates were required to submit nominating petitions of 1,000 signatures by 4 p.m. Monday to the state Elections Division. Former Bogota mayor Steve Lonegan and Alieta Eck, a doctor, are running on the Republican side.

Pallone, a 14-term House member from Long Branch, said he intends to spotlight his 25-year record in Congress.

"I'm in this race because families in our state and throughout the nation are hurting, and I believe that we have a responsibility to roll up our sleeves, get to work and help," Pallone said in Trenton, after turning in his paperwork to run. "Throughout my career, I have been committed to public service and to the idea that, no matter, the size of the challenge, I would continue to stand and fight and work toward sensible solutions."

Although Pallone can tap into a $3.7 million war chest for the race, Booker is viewed as the candidate to beat because of his national prominence and charisma. The mayor, who had declared his intention to run in 2014 before Lautenberg died, has about $1.6 million cash on hand in his Senate campaign account.

Booker is is well-known from his TV appearances, social media presence and for running into a burning building last year to save a neighbor.

Between the Republicans, Lonegan is the better known. Lonegan lost to Gov. Chris Christie in the 2009 GOP primary and lost a 1998 race for the U.S. House. He is a consultant to Americans for Prosperity, a conservative group founded by the billionaire Koch brothers.

Murray, the Monmouth University pollster, said the lack of interest in the Senate race shown by Republicans such as state Senate Minority Leader Tom Kean Jr. and state Sen. John Kyrillos is a sign.

"This is unprecedented and they are facing the embarrassment of having any known office holder willing to run," Murray said. "Everyone has written this seat off except the Democrats."